1. Field of the Invention
The present invention relates to a photocurable resin composition, in particular, to a photocurable composition suitable as a coating material for optical fiber.
2. Description of the Background Art
An optical fiber, especially an optical glass fiber is produced by applying a coating material onto a quartz fiber, because the quartz fiber is fragile and easily damaged.
In the production of optical fiber, a resin coating is provided immediately after drawing a molten quartz fiber. Generally, two coatings are applied: a relatively soft primary, and a harder secondary coating. A coating material with a high cure rate is required so that the glass fiber can be produced at a high production rate. When the cure rate of the coating material is low, the productivity of the optical glass fiber cannot be improved, because the drawing speed must be reduced.
Also, characteristics required for a cured coating material include little physical change during temperature changes over a wide range, and high durability and reliability in a variety of environmental conditions.
Further, coated optical glass fibers are often used in a ribbon assembly. In a ribbon, a plurality of coated optical glass fibers is bonded in one structure by a photocurable matrix material.